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Sven-Erik writes "Due to subtle variations in the Earth's orbit, researchers have calculated that the next Ice Age is due within 1,500 years. However, a new study suggests greenhouse gas emissions mean it will not happen that soon (abstract). 'Dr Skinner's group ... calculates that the atmospheric concentration of CO2 would have to fall below about 240 parts per million (ppm) before the glaciation could begin. The current level is around 390ppm. Other research groups have shown that even if emissions were shut off instantly, concentrations would remain elevated for at least 1,000 years, with enough heat stored in the oceans potentially to cause significant melting of polar ice and sea level rise.'"

No, I'm here. What did you want to know? Getting off the Earth? That's easy:

* Orbital velocity is root (R(e) * g), where R(e) is the radius of the Earth (6378000 meters), and g is the surface gravity (9.80665 m/s^2). That works out to 7908 m/s* Kinetic Energy is 0.5 * m * v^2. Thus kinetic energy to reach orbit is 31.27 MJ/kg.* One kiloWatt-hour (kWh) is the common unit of electric energy. 1000 W * 3600 seconds = 3.6 MJ.* Therefore it takes 31.27 / 3.6 = 8.7 kWh/kg to get something into orbit.* Multiply by your local electric rate. Where I an now, that works out to $1/kg, about what potatoes cost at the local market.

So getting off the Earth is cheap, if you use energy efficiently. You haven't been, though. You have been using about the least efficient method available: chemical rockets. The best rocket fuels only have a bit under half the energy needed to get to orbit (15 MJ/kg), and the engines are around 2/3 efficient, which leaves you at around 10 MJ/kg. So the fuel can't even get itself to orbit, much less anything else, like cargo. You end up using a lot of fuel to lift a smaller amount of fuel part way, then use that to push an even smaller amount a bit further, and finally that last bit pushes a very small cargo to orbit. For those who understand math, that is an exponential ratio of fuel to cargo, where the exponent is the ratio of mission velocity / rocket exhaust velocity. For chemical rockets, that works out to 2-3, depending on which fuel. So you use e (2.718...) raised to 2-3 power as much fuel as cargo that gets to orbit.

The answer is quite obvious: use something else. Something that has better efficiency, so you are not slaughtered by the exponential. There are a number of choices. Which one you use depends on a number of "mission requirements": What are you launching, how often, how much up front development money you can spend, how much risk do you want to take, etc.

OK, that takes care of getting out of *this* gravity well. What next?

(1) Don't go right down another one. The Moon and Mars can wait till you build up some infrastructure. Use near Earth asteroids first, followed by other asteroids, including the ones orbiting Mars, as a source of building materials. You can use efficient electric thrusters as long as you are not diving down a gravity well.

(2) Don't send humans first. Humans have all kinds of picky needs about temperature, pressure, food, radiation, etc. Robots, remote controlled, and automated equipment (which I will call just "robots" for brevity) are not as sensitive. Send robots first, have them build stuff up. Once you have enough stuff in place and can support the humans, then they can come.

Describing the impact of global warming as "a bit more war and some starvation" is rather like describing the situation of living living in Pompeii in AD 79 as being "minorly inconvenienced by relatively minor geological events".

How do you know that? Some models predict increased desertification in the mid latitudes but then many show increasing crop productivity at more northern latitudes. What we do know is that during previous ice ages the human species went through some bottleneck events that reduced our numbers to what we would now considered near extinction for a large animal species.

How do you know that? Some models predict increased desertification in the mid latitudes but then many show increasing crop productivity at more northern latitudes. What we do know is that during previous ice ages the human species went through some bottleneck events that reduced our numbers to what we would now considered near extinction for a large animal species.

Go visit the tundra, tell me what you think that place will smell like when it thaws.

Sure, in about 1000 years when the toxic rot has run its course, there will be productive land there able to grow crops, but it won't get there without a lot of pain during the transition.

Intrinsically, people are inconvenienced by change, change of this magnitude is inconvenient enough that people will go to war over it.

So? Homosapien has been going to war since before we left the trees (at least we're pretty sure since most of our closest relatives wage war). We've had war since we've been around and it's never come close to wiping us out, on the other hand we're pretty damn sure that glaciation has come really close to killing us off. I'll take a bit more war over a near extinction event that we can't control.

It appears you've never been in a real war. Neither have I but I've seen the pictures from WW I and WW II and read the statistics. You can academically say, "Well they were an inevitable event in the adaptation of 19th century nation-states societies to the 20th century Industrial Age", but that doesn't mean you want your kids to go through that sort of thing -- and I mean the devastation of WW II in Europe and Asia, not the relatively light touch the US got. I'll take a multi-hundred year climate change to which we can adapt over a ten year series of conflicts later called WW III.

Well, according to the article, you can. If we were to find our planet cooling, we could just release more CO2 into the atmosphere. Heating from global warming takes on the order of 20 years to take full effect. Ice ages occur on geological time scales which are much larger. Plus, it is far easier to put carbon into the atmosphere than take it out. So our best bet is to wait until we observe cooling and then react to it. Right now, however, we are seeing a noticeable increase in temperature. This suggests t

Galciation has never come close to killing off any humans in Africa. We've proven ourselves to be the most adaptable mamal to walk the earth, starting from the African savanah and migrating to the frozen Siberia, across continents and oceans to nearly every land mass on the planet - all before we discovered any form of machinery - no metal, no steam power, no electricity. I severly doubt any form of global warming (or cooling) could wipe out humanity. 1000's of other species on earth? Yes. New ones will eve

Go visit the tundra, tell me what you think that place will smell like when it thaws.

It'll smell like taiga because that is what it'll become.

Sure, in about 1000 years when the toxic rot has run its course, there will be productive land there able to grow crops, but it won't get there without a lot of pain during the transition.

Or we can change the terrain to suit our purposes.

Using what? Oil, or Nuclear? Nothing else has the the total energy capacity to even attempt "TerraForming" on that scale. I've watched Florida finish its transformation from swamps to agriculture and beach condos - it took 100 years and LOTS of diesel fuel. Today's Taiga doesn't support much in the way of food crops, it will take major waterflow "improvements" to make much usable farmland out of today's Tundra/Taiga after a thaw. Look at a globe, Florida is pretty small compared to Siberia + Canada.

Intrinsically, people are inconvenienced by change, change of this magnitude is inconvenient enough that people will go to war over it.

They'd go to war anyway. At least with AGW, I know I'm not crippling my society before the next wave of wars starts.

I don't "know" in the sense that certain faith based folks "know" that they'll be the ones saved.

I do, however, know in the sense that I've read a lot about it, including impact models ranging from US government predictions (military [guardian.co.uk], civilian [foxnews.com]), international studies [www.ipcc.ch], many of which predict widespread starvation [usnews.com] and chaos [msn.com].

He's making whatever argument allows him to rationalize continuing barfing millions of years of sequestered carbon into the atmosphere in the space of a few centuries. He doesn't care what happens in fifty or a hundred years. The world exists simply for his enjoyment.

I'm almost certain afidel is in a First World country in the Northern Hemisphere. Therefore, for him, having the entire Northern Hemisphere uninhabitable is a bigger deal than the war and starvation which will mostly occur in Third World countries.

It's sort of like how many people, if given the chance to vote between spending millions of dollars feeding starving Africans, or spending millions of dollars to revive Firefly, might pick Firefly.

Feeding starving africans will do NO good. Instead, far better to help them feed themselves. Best way is to get businesses going with them. IOW, even helping firefly does more to help africa then simply giving food to ppl that are then cut off later and starve again.

Unfortunately, the model for aid to countries with starving people has been to deny them any semblance of security. The US (and other countries) ship in massive amounts of food in a generally inedible form - raw grains, etc. This is then given to various bodies within the country with starving people. Some of this ends up being sold for the enrichment of people that weren't starving to begin with. Some of it ends up being dumped along the road because it is too much trouble for them to actually distribute.

The truely awful scenario is the family found dead of starvation sitting around with a bag of raw wheat grain sitting there at their feet. Without a flour mill the raw grain is pretty much useless except as an animal feed, and all the animals were eaten last week.

We is the US sending bags of grain to warlords hoping they will distribute this to their "subjects" that they desperately want to keep in total subjugation? Why is the US sending bags of grain to the government of a country that has historically totally neglected their rural population? Why is the US sending bags of grain in the first place? Oh, because we have a surplus of it and it doesn't really cost anything to ship the surplus overseas.

The end result of this is the people still starve. Even if they get the food aid, it doesn't help solve the problems of why they are starving in the first place. Nor does it teach the people anything about getting out of their predicament. Food aid has been a curse to Africa since day one and nobody on either side seems to be learning anything from the history of failure.

That is kind of what happened. Back in the 60's, we DID give loads of food for disaster areas. And it was the right thing to do. The problem is, that we kept doing it. As such, we put the local farmers out of business. They can not compete against free. THen we slowed down the aid, but the farmers are gone. That is why I keep saying that a better model is to help these ppl establish businesess and farms and schools and roads, etc. If these locals can actually be made to help themslves, then they are bette

Why do you think so? Global warming is certainly much more pleasant than global cooling, and the warmer periods in Earth's history have generally been more conducive to life. The only real problem with warming will be the social-political instability that results.

Hating ice ages doesn't mean liking global warming. If you want to prevent the planet from cooling into an ice age, you don't need to warm it up above present temperatures. You just have to keep it from cooling below present temperatures.

Human civilization has adapted itself to a relatively stable range of climate over the last 10,000 years. Large warming or large cooling pushes us outside of that range. It may be costly to adapt our civilization to a completely different climate, particularly if it happens "fast" (century time scale). Thus, it's possible to hate both global warming and "ice ages".

If you want to use the greenhouse effect to prevent the planet from falling into a glacial period, then you should want to save fossil fuels for when we need them, rather than using them up now, when we don't. That is, dole them out slowly over thousands of years to keep the interglacial climate stable, as the next glacial period gradually deepens, instead of our current course of using them up rapidly and elevating temperatures well above the Holocene climate range.

Besides which, this study is controversial. Everyone agrees that we will see another glacial period someday, barring human intervention. The question is when. This study suggests 1500 years; a number of others have suggested that the next glacial period isn't due for as long as 50,000 years. Which is even less of an argument for global warming.

Unfortunately, the effects from the ice age will not be apparent for another 1,500 years, while, on the other hand, the ice caps are already starting to melt. Though a small amount of global warming might be beneficial in the future for preventing an ice age (who knows what environmental impact THAT would have), it is very likely to be seriously detrimental for the next few centuries until then.

Very little is known on how exactly an ice-age begins AFAIK. Is it rapid onset? Slow? It may begin with higher than normal snowfalls & a shorter growing season in the northern hemisphere inducing wide-spread crop failures in that part of the world which is currently feeding the other part thus rendering your reassurances hollow.

Scientists (you know, people who actually study these things) predict an ice age with an extremely wide variation. Some say 1500 years, others 50,000 years. Unless you can find data showing that the next ice age will start within the next century, I'd say global warming is the more pressing matter than a hypothetical ice age.

If such a thing were to happen, it isn't that hard to move. In fact, it has been done in the past repeatedly. Numerous ancient Roman ports have been excavated well inland.

Further, if warming trends were to continue, the grain belt of the midwestern US would stretch up into Canada, potentially doubling the population support capacity of the farms of North America, to say nothing of those of Russia.

Further, if warming trends were to continue, the grain belt of the midwestern US would stretch up into Canada, potentially doubling the population support capacity of the farms of North America, to say nothing of those of Russia.

Please note that moving the "grain belt latitudes" into say, central america, would somewhat reduce our total grain production simply due to lack of land.

One requirement to having ice ages is having a lot of land at high latitudes, which means a huge food crunch during ice ages. There's just less biomass.

Being flooded sucks, but at least theoretically florida could be a nice fishery.

Further, if warming trends were to continue, the grain belt of the midwestern US would stretch up into Canada, potentially doubling the population support capacity of the farms of North America, to say nothing of those of Russia.

Ah, but that assumes the grain belt expands, and not, as emperically determined, moves northwards. You see, just because Canada's getting warmer, doesn't mean the US isn't as well, and former grain belts turn into basically dust belts because it's too hot to grow anything - at least

Well, if New Orleans and Dallas are any indication (both of their downtown centers are below the local water level), the seawall building business is going to heat up. If Galveston's proven anything, it's that a 17' seawall is extremely effective, and durable over the 100-year term.

Either way you look at it, water is the enemy. Let's get rid of the stuff! I propose a giant space straw.. we'll just stick a big pump on the moon and suck it up to the Lunar surface. Instant space beachfront property.

If you just stick a straw in the ocean and make it long enough, the end will be in space. The vacuum will obviously start sucking the water up immediately, and it will continue to flow until you pinch the end.

> What about the ones that live in areas that are going to be covered in water?

Thanks to civil engineering, building permanent structures in areas that are submerged is quite do-able (think: causeway, oil rig). In stark contrast, glaciers are a very, very BIG problem. There's really no good way to build a permanent structure in the middle of a thick glacier field. If you build on top of the glacier, pressure melts the ice & causes the structure to slowly sink into it. If you refrigerate the contact points to keep the ice from melting, the structure moves with the glacier. If you try to bore holes down to the bedrock & build concrete pilings through the glacier, the glacier's motion will snap them like twigs. It's not necessarily *impossible*, but the engineering problems involved make open water look like a neatly-cleared urban vacant lot in a big city by comparison.

I'm still somewhat amused by sea-level alarmists whose flood maps just assume that people will passively abandon hundreds of billions of dollars worth of low-lying real estate & allow it to become submerged, instead of doing more or less the same thing developers in Florida have been doing for the past century -- digging holes for fill dirt, raising the terrain, and building on pilings where appropriate. Hell, my neighborhood, and the land my house sits on, was submerged under several feet of water for thousands of years on the day I was born. ~20 years later, the area was drained, dredged, filled, and turned into nice houses on a big manmade lake. I know, because my neighborhood's HOA has been fighting with FEMA for the past 10 years to update the official flood map for my neighborhood from -2 feet to 12 feet, because nobody ever bothered to update the official county elevation map after the developer terraformed the neighborhood into dry land.

Actually, this raises another point... lots of the Global Warming flood prediction maps based on land elevation for South Florida are just plain wrong, for the same reason as the map in my own neighborhood -- developers over the past 100 years dredged, filled, and raised the land, and nobody ever bothered to update the official terrain maps. The flood models are wrong, for the same reason why hurricane storm-surge models have been wildly wrong in pretty much every hurricane since 1940 -- the surge models -- like Global Warming Flood Models -- assume the existence of a natural coastline that hasn't existed for *decades*.

Are sea levels rising? Probably. Are they going to rise more? Almost certainly. Are waterfront neighborhoods going to be abandoned to rising water? No way in hell. They'll just get rebuilt on taller foundations every 50 years or so when a major hurricane blows away whatever's there now.

Actually, in terms of surface area, more would be covered by glaciers than by water

Why do we have to choose between death by ice and death by fire? We've already released enough CO2 to prevent the next glacial period. If we stopped emitting CO2 then we could prevent the hell and high water that is predicted from continuing on with business as usual.

Wonder how many hypocrites who previously excoriate all climatologists who caution about global warming as corrupt and biased instantly trumpeting that these brilliant, honest, decent climatologists have to be right because the end result is one that they want.

It's not hypocritical to criticize those those using global warming to push for extreme changes to actually have meaningful proof that their hypotheses are valid before breaking the economy. The current study, if it is valid, would just make it clear that the climatologists were not as right as they had been trumpeting and that distrust of their hasty conclusions was the correct course.

Adding CO2 has an effect because there are non-overlapping areas of the absorption spectra between CO2 and other greenhouse gasses. Doubling CO2 will add a forcing of 3.7 W/m^2. This will warm the atmosphere somewhat. The warmer atmosphere will be able to hold additional water vapour. This will warm the planet much more as water vapour is a much more potent greenhouse gas. So you are right to worry about water vapour. This is expected to be one of the larger feedbacks from increased CO2.

Their argument is actually that the slight warming caused by CO2 will increase the water vapor in the atmosphere, which will cause the lion's share of the continued warming, until they hit a tripping point in the arctic that'll release megatons of frozen methane which will lead to a catastrophic warming event. Depending on who you listen too climate sensitivity is between 1.4 to 2.5; if we look at 2, it means that for each doubling of CO2, the mean global temperature goes up 2 KBest estimate for abs [nasa.gov]

I buy that CO2 could prevent or delay the onset of an ice age. What I don't by is the suggestion that an ice age is due to start 1500 years from now. Looking more carefully, I see that the value of CO2 level required to prevent an ice age 1500 years from now is below the pre-industrial level. In other words they've predicted an ice age that would, under no conceivable circumstance, occur and then said, look, it won't occur because of CO2. Yes, but then again our lakes aren't frozen in the summer now because of CO2. Maybe we should send out a press release.

I think you're understanding. The pre-industrial level was 280 ppm. The amount required to prevent the coming ice age is 240 ppm. Therefore human CO2 emissions are not required to prevent this ice age. It's also why nobody else has predicted that an ice age will start in 1500 years.

Perhaps their prediction was based on a model that ignores human involvement, and attempts to predict carbon declines from natural sequestration, such as tundra, peatbogs, and the like.

Eg, "if no human activities had occured, co2 levels would drop below 240ppm, due to natural sequestration. This would result in an iceage, until volcanic sources of c02 increases levels sufficiently to melt the glacial ice. Our model predicts that this event would occur 1500 years from now, under the above constraints."

In the late 1990s I remember they were out there with an interesting take that not only was the greenhouse effect real, but that we should promote it because it would "make Greenland green again" and otherwise unlock many areas of tundra and for conventional agriculture and human expansion.

That's one theory. Another is that it was named "Gruntland" because of the shallow bays around it (grunt being a term for shallow bottom related to the English word aground). We probably won't ever know the truth. Other than that it hasn't been green for thousands of years... at minimum.

Under the ice on Greenland we would find lots of rock and gravel. Not much in the way of arable land. The people who think otherwise have never seen melting tundra or a glacier bed.

One thing's for certain: whether coastal cities are under 20 feet of water or up to their asses in ice 2000 years from now, there will still be politicians pointing at each other over whose fault it is.

It's hard to get funding for an experiment that takes two identical planets and changes the global CO2 concentration on one.

Climatology is an observational science like geology or astronomy. Models can be checked. It's not just curve fitting to the temperature record: climatologists figure they're on the right track when their models predict phenomena like El Nino.

The mandatory response is, of course, ability to occasionally predict something is not an indication that the level of certainty of all stated conclusions is as great as claimed. Whether or not level of certainty has been overstated is not something that yields itself to peer review. Basically, peer review can only answer the question "is this definitely true or is there a flaw in the observations or conclusions." Whereas, level of certainty can only be estimated by answering the question "is this plaus

Astronomy and geology are certainly not "observational sciences" in the sense you use that phrase. Experiments are not only possible in astronomy and geology, they are performed routinely. I don't know much about geology, but there are a lot of notable experiments in astronomy, from ancient times to yesterday. For example, the determination of the circumference of Earth by Eratosthenes, the discovery of the planets beyond Uranus, the observation of neutron stars, the background cosmic radiation, the discove

I think the gold standard should be it's utility. Try googling, you will find dozens of forward predictions similar to these...

1. The phenomena known as "Polar amplification" was predicted before it was observed.
2. The phenomena known as "Stratospheric cooling" was predicted before it was observed.
5. Accurately predicted the climatic impact of the Mt Pinatobo eruption.

These sort of tests don't even start to list the basic predictive skill a climate model needs to be considered useful, such as the ocean currents, air pressure patterns, the roaring forties, monsoons, ENSO, the formation of tropical cyclones in the right geographical locations in the right season, the morning clouds in the Amazon burnt of by the sun, sea ice extent, all these things and much more must be accurately hind-cast before you can even start to ask "what if" questions.

Indeed. As is hominid evolution. Just because we are basing theories off of observed and currently happening phenomena does not mean that the science need be any weaker than working with phenomena for which active processes have largely ceased. Besides, geology is a ludicrously bad example. Just how many times do you get to observe Archean rocks form? That climatology is researching active processes is a benefit, not a negative. Helluva lot more difficult to test specifics of ancient geology or Big Bang cos

Everyone else is fairly well aware of the scientific method and peer review.

However, we have known for a few years that the Earth's orbit has been rounding out, which is when it gets colder. This was among many points covered on slashdot along with solar output and geological methane release that demonstrated that the Earth's climatic shift has been primarily due to CO2 levels. If CO2 levels had not gone significantly beyond their 1700 levels, we would be experiencing the starting signs of cooling over th

Actually, the process with climatology was subtly different, something like

1. Someone got a PhD in science

2. They began collecting data and observe what's happening

3. They published some papers and gathered about 10 more people, who had gone thru 1 and 2

4. They published more papers

5. They collected more data, and convinced their government that even more data is necessary

6. They got more equipment, more data, came up with some ways to put these data together

7. Then they refined their hypothesis, got more funding and more students

8. Then they got publicity by semi-literate journalists, and it all went political. Unfortunately, unlike the people who play politics, the people who did the research were not prepared for the tricks on the political side.

9. Even unfortunatelier, nobody else was prepared to understand or argue sensibly the "tricks" on the research side

10. Ever since, it has been one giant downhill race in lies, accusations and misunderstandings, to the detriment of science

11. When it should have been a harmonious transition to getting more understanding of the topic, and gradually and smoothly planning and executing whatever action would be necessary.

It started in 1824 when Fourier predicted the IR absorption properties of CO2 while inventing spectroscopy. Tyndall confirmed the prediction in the 1850's and finally in 1896 Arrhenius started looking into the effects of industrial CO2 emissions on the climate (not sure if any of them had a phd). The idea was dismissed for about 50yrs due to the argument that water's broad IR absorption spectrum obscured and therefore cancelled CO2's narrower IR absorption spectrum. It wasn't until spect

Global warming means that we're changing a massively complex system. And like all massively complex system, when you tweak the parameters beyond a certain point, the system as a whole can itself wind up altering other parameters drastically as it seeks a new stable state.

Or, to put it simply, global warming could potentially lead to a sudden and drastic cooling:

Anything we do, "could potentially" do something, or nothing, or upset part of Mother Nature that proves unexpectedly fragile.
Unless Mankind goes away, we will continue to influence the environment forever.
I suggest doing Nothing as the only possible prudent course of action.

Of course we're going to have an impact on our environment. The difference between us and the first cyanobacteria [scientificamerican.com] (that caused massive climatic upheaval when the oxygen levels on earth reached a tipping point where other first generation single celled entities died off en masse) is that we have the ability to reason, if we use it, and chose options that will not be as destructive to the ecosystem that we are a part of, and upon which we rely for our lives.

Another fallacy is considering that Nature is stable & that all man-linked influences are inherently bad for the kind of environment we want to live in. First Off, Nature is NOT stable. There would be climate change whether or not mankind was here or not. Secondly, I know that the popular environmentalist meme enshrined in so many books & movies (Jeff Glodblum in Jurassic Parc grunting "Mankind Bad, Mother Nature Good" among them) is that all man-linked influences are bad. I just don't believe the m

The Earth's climate is a massively complex system that has been constantly changing for billions of years. The climate wasn't static before we showed up.

Problem is we don't have the slightest clue what climate change is sustainable by the Earth and what changes aren't. If you think of the Earth's life as one 24 hour period, we've been around for a couple seconds. One thing we do know for sure is the Earth has sustained much war

The Earth certainly has. But humans have a pretty narrow temperature band in which they can live. Humans sweat based temperature regulation would not have functioned over most of the Earth when the dinosaurs ruled.

But really, this isn't about the Earth's survival. It's about Humans. You're right - we haven't been around that long. And it seems that our refusal to acknowledge that we're soiling our niche will ensure that we aren't around for all that long, either.

That's a tad different. During the last ice age we didn't have the ability to ship food thousands of miles and make user of the land that was now useful for agriculture. Also, we didn't have insulation and heating technology like we do today.

An ice age isn't the greatest thing ever, but life has a much better chance of coping with it effectively than the rather extreme changes in climate that we're setting off.

Just up the road a ways (ok 100 KM) is a mountain that is capable of sustaining a sizable population for 10 years, with stores as well. Many nations have similar areas. No, a comet would NOT wipe out humanity 100% unless it took out most of our atmosphere or the planet itself.

Nothing we do can combined cause global scale changes on the planet, which is nice, because then I can keep doing whatever I want.

The worst part is that very little is required to make very large impacts on carbon emissions. If everyone in the US bought a car that had half the horsepower that the car they currently own has, they could make a huge impact on their emissions.